The present invention relates generally to machining apparatus and more specifically to an improved cutting wheel well suited for use in machining of a wide variety of materials and in particular various types of elastomeric materials such as synthetic rubber and the like.
Machining of different types of materials presents widely varying and often conflicting problems. One tool design may be exceedingly effective for machining and/or shaping of one type of material and yet totally ineffective on another type of material. Various factors contribute to need for often widely varying approaches to machining of different materials such as hardness, ductility, resiliency, etc.
Elastomeric materials such as for example tire treads have been particularly difficult to machine presumably due at least in part to the inherent resiliency of the material. Typically tire tread machining has been accomplished by various types of abrading devices such as rasps, grinding wheels, and wire brushes. Because such devices rely upon a friction type "wearing" action (as opposed to a cutting action) in order to remove material, substantial amounts of relatively fine dust-like particles are generated which are difficult to contain. Further, because the process is dependent upon friction for effectiveness, it is difficult to perform at an economical speed of production without the resulting heat becoming excessive to the point of scorching of the underlying surface. Further, the use of rasp blades and the like also tends to produce many cuts or tears in the underlying surface material which close up as the rasp moves on to other areas. These cuts or tears are particularly undesirable in the case of retreading motor vehicle tires as they may result in a weakening of the tire casing which may not be totally overcome by the subsequent new tread bonding process.
The present invention, however, overcomes the aforementioned problems in providing an improved machining device incorporating replaceable cutter inserts which are specifically designed to effectively and efficiently machine elastomeric materials as well as a wide variety of other materials. The cutter inserts incorporate a unique design which renders them particularly well suited for machining elastomeric materials including preparation of tire casings for retreading. The cutter inserts each include a sharpened corner edge having an acute included angle which operates to effectively pierce the elastomeric material as the carrier wheel is moved axially across the workpiece to be machined. A linear edge portion extending between the corner edges operates to complete the machining action by severing chips of material from the workpiece. Because the insert is designed and mounted with appropriate rake and clearance angles, the stock removal is accomplished by a true machining operation rather than by an abrading action. This machining action for stock removal is also accomplished without the generation of high temperatures thus avoiding the possibility of scorching the underlying surface of the workpiece. Further, because the stock removed is in chip form as opposed to the dust-type particles removed by abrading operations, the need for dust collection equipment is substantially reduced.
The insert also incorporates integrally formed means for accurately positioning the cutting edges when the insert is secured to the carrier wheel thus greatly facilitating replacement thereof. Further, rotation inhibiting means may also be integrally formed on the insert to thus assure the cutting edges are retained in the proper orientation with respect to the workpiece. Additionally, because the cutter inserts do not rely upon high heat generating friction for stock removal as in abrading devices, the cutting edges remain relatively cool thus insuring a relatively long operational life.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.